The production of crystalline copper salts, such as for example copper hydroxide (Cu(OH)2), copper-(I)-oxide (Cu2O), copper-(II)-oxide (CuO), alkaline copper carbonate (CuCO3×Cu(OH)2×H2O) or alkaline copper nitrate (Cu(NO3)2×3Cu(OH)2×2H2O) as well as mixed salts, such as for example copper oxychloride (CuCl2×3Cu(OH)3) and alkaline copper sulfate (CuSO4×3Cu(OH)2) generally occurs either through the oxidative leaching or metallic copper or through a stoichiometric chemical reaction of soluble copper salts with the appropriate base (preferably a strong base such as lye) and/or through consecutive reactions of the created finely dispersed substances.
One example for oxidative leaching is the preparation of copper oxychloride pursuant to the reaction:4Cu+2CuCl2+2HCl+½O2→6CuCl+H2O  (1)6CuCl+1½O2+3 H2O→3Cu(OH)2×CuCl2+2CuCl2  (2)
Examples of chemical reactions of soluble copper salts are the production of copper hydroxide pursuant to the three methods below:
Copper Hydroxide Method ICuSO4+Na2PO4→CuNaPO4+Na2SO4  (3)CuNaPO4+2NaOH→Cu(OH)2+Na3PO4  (4)or
Copper Hydroxide Method II3Cu(OH)2×CuCl2+2NaOH→4Cu(OH)2+2NaCl  (5)or
Copper Hydroxide Method III3Cu+1½O2+3H2O→3Cu(OH)2  (6)
Further examples include the production of alkaline copper carbonate pursuant to the reaction:2Cu(OH)2+CO2→CuCO3×Cu(OH)2×H2O,  (7)of alkaline copper nitrate pursuant to the reaction:4Cu(OH)2+2HNO3→Cu(NO3)3×3Cu(OH)2×2H2O  (8)and the so-called Bordeaux mixture pursuant to one of the following reactions:CuSO4+Ca(OH)2+4CuO×SO3×3H2O×3CaSO4  (9)(in the case of excess CuSO4)CuSO4+Ca(OH)2→[Ca(OH)2]3CuSO4  (10)(in the case of excess Ca(OH)2)
The copper salts generated in these reactions usually have a particle size between about 1 and about 10 micrometers (μm) and a particle surface area of about 1 to about 10 m2/g. The structure of the crystalline material produced will depend upon the chemical composition and, to a certain degree, upon the production method utilized. For example, copper hydroxide crystals produced according to the of the copper hydroxide produced pursuant to Method II are generally available in a needle shape, while the crystals of the copper oxychloride produced through oxidative leaching pursuant described above are generally available in an octahedron shape.
The biologically active portion of such copper compounds is the copper ion, which can be released from these water-insoluble salts and which is available through a natural, so-called slow-release process for the medium that is to be protected, e.g., plants, wood or water. In the case of fungicidal and bactericidal applications of such compounds to plants, the respective copper salt compound is typically sprayed onto the plant's leaf surface to form a copper salt particle film substantially covering the leaf surface.
By reducing the particle size of the copper salt particles, it is possible to reduce the quantity of copper salt that has to be applied per leaf surface while at least maintaining the same effect. One way to achieve this result is by controlling the production conditions, especially the temperatures and concentrations of the involved substances. This way the particle size can be lowered from 50 to about 10 μm, possibly to about 1 to 3 μm. It is thus possible to increase the effectiveness towards special types of fungi from the existing 80% to 100% or to main an existing 100% effectiveness towards special fungi while simultaneously reducing the copper salt dosage rate that is required per hectare.